Cyanoethyl starch ethers



, spending to 2.4 cyanoethyl groups Patented 6, 1943 i 2,316,129 FFlCEoranos'rm STABOEITHEBS LolliaILBw V Huntingdon Valley. arulll'n L.

Honk, P elphil, Pt,

alllgnerstoluhmb Haas Company, Philadelphia, 2a., a corporation ofDelaware No Drawing- Application February 21, 194:, Serial No. 4:1,:41

- s Claims. (Cl. 260-209) This invention relates to ethers of starchwhich are insoluble in water and in which hydroxyl groups are etherifiedwith p-cyanoethyl groups. This invention iurther relates to the process01' reacting starch with acrylonitrile in the presence of a strongalkali, whereby the water-insoluble p-cyanoethyl starch ethers are.

produced.

The p-cyanoethyl starch ethers of this invention are prepared by mixingbetween about 0 and about 40 C. starch, a dilute solution of a As astarch there may be'used root or grain starches, such as potato,tapioca, corn, wheat, or the like. As a strong alkali there may be usedan alkali metal hydroxide, such as lithium, sodium, or potassiumhydroxide, or a strong organic base, such as tetraethyl ammoniumhydroxide, benzyl trimethyl ammonium hydroxide, dibenzyl dimethylammonium hydroxide, or the like. From 0.025 to 0.5 mol of awater-soluble, strongly basic hydroxide per glucose unit oi the starchmay be used as a catalyst for the reaction in solutions 01 0.1% to about2%. The proportion of acrylonitrfle should be at least three mols perglucose unit. No advantage is gained, however, in mixing more than fivemols, as amounts above this proportion cause no additional reac-,

tion.

In reacting starch and acrylonitrile in the presence of a dilutesolution oi a strongly alkaline catalyst, the starch need only besuspended in the solution, acrylonitrile added, and the mixture stirreduntil the cyanoethyi ether precipitates. While the temperature of thereacting mixture may be as low as 0' and as high as about 40' 0., theoptimum temperature range is from about 20 to about 30' 0., or roomtemperatures. Under such conditions, reaction is complete in three tofive hours. The time required may be shortened by raising thetemperature.

The following examples are presented to illustrate the invention:

Example 1 To 330 parts of potato starch in 3,000 parts of water therewere added 100 parts of 20% sodium hydroxide and 530 parts ofacrylonitrile in small,

successive portions. The reaction mixture was stirred until all thestarch was precipitated,

about three hours being required. The product was then filtered, washedwell with water, and dried. It contained-11.6% of nitrogen, correper sucose unit.

Example 2 To a paste containing 33 parts oi tapioca water-soluble,strong alkali, and acrylonitrile.

dry. it was brittle.

(3 mols) of acrylonitrile. The reaction mixture was stirred at roomtemperature until a precipitate formed, about four and one-half hoursbeing required. The product was filtered-,washed, and dried, Itcontained 9.3% 01' nitrogen.

Example 3 To 33 parts of potato starch in 200 parts oi water there wereadded 20 parts of 20% sodium hydroxide and 53 parts of acrylonitrile.The mixture was stirred at 0 to 5' C. for seven hours,

by which time the desired reaction product had completely separated. Theliquor was poured oi! and the product was washed substantially free ofcaustic and spread out to dry. When partially dry, it was veryrubber-like but, when completely The product as formed is' a gummy solidwhich becomes-hard-on drying in an oven. While it tends to swell inwater, it is completely insoluble therein. It is swelled by 75% aceticacid but is insoluble in the common organic solvents. It canlie-dispersed in water, y milling. with an emulsifying agent such astriethanolamine oleate. This dispersion is useful as a coating agent fortextiles,.iorming a washfast finish which imparts weight and stiiinessto the fabric. The product is also meiul as a binding agent for.pigments and dyes for printing textiles.

We claim: g 1. The rn'ocess i water-insoluble cyanoe'thyl ethers-intstarch which comprises mixing'between 0 'andFaboutiv C. starch andacrylonitrile in'a dilute solution of a watersolublepstrongly basichydroxide, the proportion 01' acrylonitrile being at least three molsper glucose unit of the starch.

2. The process of preparing water-insoluble p-cyano'ethyl ethers ctstarch which comprises reacting by mixing starch and at least three molsof acrylonitrile per glucoseunit oi the starch in a 0.1% to 2% aqueoussolution of a water-soluble, strongly basic hydroxide and maintainingthe temperature of the mixture between 0' and about 40' C. untilp-cyanoethyl starch ether has precipitated. V

3. The process of preparing water-insoluble p-cyanoethyl ethers oistarch which comprises reacting by mixing between about 20 and '30 C.starch and at least three mols of acrylonitrile per glucose unit of thestarch in a 0.1% to 2% aqueous solution of a water-soluble, stronglybasic hydroxide.

4.-The process of claim 3 in which the hy-. droxide is sodium hydroxide.

5. The process 01 claim 3 in which the starch is potato starch.

LOUIS H. BOCK. ALVA L. HOUK,

